1. Field of the Invention
This invention relates to improved vanes for removing entrained or suspended droplets or particulates in a gas stream.
2. The State of the Art
Many chemical and other industrial processes create a gas stream that includes non-gas particles that must be removed from the gas stream. These particles are typically liquid droplets, but can also be solid particles.
Perhaps the most typical of methods for removing these unwanted particles is a device which causes the gas/particle flow to change direction. Because the particle has a higher density than the gas of the stream, the momentum of the particle will tend to make the particle travel in a straight line and not change direction as quickly as the gas.
For example, in the case of a stream of water droplets in air, the gas stream can be passed through a wire mesh; the liquid droplets cannot negotiate the tortuous path through the mesh and so they land on and adhere to the mesh by surface tension, and then run off by gravity from the mesh screen.
Another device includes a series of vanes arranged parallely, each vane being a thin sheet that is formed into hills and valleys. The vanes are arranged spaced closely together. The gas stream enters one side and takes a zig-zag path to reach the other side. The entrained droplets cannot negotiate the rapid zig-zag and impinge on the vane, where they cling and run down the wall.
Various companies provide vane type demisters comprising a multiplicity of closely-spaced parallel sheets all providing the same geometry tortuous path. Such companies include Amistco (Alvin, Tex.), Perry Equipment Corp. (Mineral Wells, Tex.), Koch-Otto York Co., Inc. (TX), Burgess Manning (Orchard Park, N.Y.). Peerless Mfg. Co. (Dallas, Tex.), and Ed. W. Smith Mach. Works (Dallas, Tex.).
One of the problems of vane-type mist eliminators is that the droplets flowing down the vanes can be re-entrained in the gas stream. Re-entrainment is more likely as the gas velocity increases, but higher stream velocities are desired for higher throughput. At certain throughputs, the gas momentum is such that much of the separated liquid is re-entrained and exits from the device; this is termed “breakthrough.”